<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		.cube{
			width: 100px;
			height: 100px;
			background-color: red;
			margin: 100px;
		}
		.parent{
			/* 开启BFC */
			overflow: hidden;
		}
	</style>
</head>
<body>
	<div class="parent">
		<div class="cube"></div>
	</div>
	<div class="cube"></div>
</body>
</html>